int ask_password_tty(const char *message, usec_t until, const char *flag_file, char **_passphrase);
+void dual_timestamp_serialize(FILE *f, const char *name, dual_timestamp *t);
+void dual_timestamp_deserialize(FILE *f, const char *line, dual_timestamp *t);
+
#define NULSTR_FOREACH(i, l) \
for ((i) = (l); (i) && *(i); (i) = strchr((i), 0)+1)